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Unread 25-10-2002, 00:05
kmcclary's Avatar
kmcclary kmcclary is offline
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Stamps vs a 555 for a one channel PWM tester

Quote:
Originally posted by wysiswyg

Hmm if they act anything like a [servo] then you should be able to control the victors with a basic stamp. I know that you can control [servos] with a basic stamp.
Well, if you're REALLY insane, yes it can. But that's the EXPENSIVE way to go... A Stamp-II is about $50 a pop... A 555 timer is about $1! (I guess you could always use a Stamp-I for it... That's ONLY 34x more expensive rather than 50x more expensive... )

BTW... Remember with a Stamp you also have to digitize the pot with a POT command, *AND* run the Victor with a PULSOUT. BOTH statements use an "ignore the world timing loop", and won't complete the statement until the counting is complete. Therefore, the higher the pot resistance (or the longer the pulse), the longer it takes to complete that statement.

It'll probably be OK for a "one pot & one Victor" situation, but if you try more of either, then under certain circumstances the POT or the PULSOUT commands may take long enough to cause an ignored Victor's watchdog timer to time out, shutting it down. (I don't know the timout value of the Victor's watchdog.) You'll definitely run into that problem quickly if you try more than a few pot and servo pairs.

FYI, That's exactly why the Robot Controller uses dedicated PIC micros for its I/O, and we have to talk to them via the infamous SERIN and SEROUT statements at the ends of the robot program's main loop...

Bottom line: Even if a 555 and a Stamp were equal cost, IMHO a 555 would STILL be a better choice!

However, it might be something fun to try for giggles... A Stamp-I version CAN use a CH Flightstick for the pots, and MAY be able to run a pair of Victors without them shutting down.

- Keith
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Last edited by kmcclary : 25-10-2002 at 00:17.
 


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